In power conversion applications, constant on time (“COT”) control is widely used in DC-DC converters since the DC-DC converters using the COT control may have a fast dynamic response. Compared to a DC-DC converter using peak current control, a DC-DC converter using the COT control has a switching frequency varied with the change in an output current signal. Especially, in a multi-output DC-DC converter, there are multiple channels each of which comprises a sub-switching converter. These sub-switching converters may share a common input voltage signal. It's desired that each of the sub-switching converters uses the input voltage signal in a time division multiplex manner. Since the switching frequency of each of the sub-switching converters using the COT control is varied, it's hard to realize the time division multiplex of the input voltage signal in the multi-output DC-DC converter using the COT control. Thus, in the prior art, the peak current control may typically be adopted to control the multi-output DC-DC converter.
Therefore, it is desired to have a solution for realizing the COT control in the multi-output DC-DC converter.